Now you see it: fixation-related electrical potentials during a free visual search task reveal the timing of visual awareness

It has been repeatedly claimed that emotional faces capture attention readily, and that they are processed without awareness. Yet some observations cast doubt on these assertions. Part of the problem may lie in the experimental paradigms employed. Here, we used a free viewing visual search task and simultaneously recorded electroencephalography and eye-movements. Fixation-related potentials were computed for fearful and neutral facial expressions, and the electrical response compared when participants were aware or unaware of the fixated stimulus. We showed that the P300 increased across repeated fixations on the unseen targets, culminating in a conscious report, likely reflecting evidence accumulation. Awareness of the stimulus was associated with electrical changes emerging at around 130 ms, with emotions of the stimulus being dissociated only after awareness had arisen. These results suggest that the earliest electrical correlate of awareness emerges at around 130 ms in visual search and that emotion processing requires visual awareness.